1. Field of the Invention
This invention relates to methods for forming an article from a continuous extrusion process and, more particularly, to methods for forming plastic articles from a continuous extrusion process.
2. Description of Prior Art
In the prior art, techniques are known for forming plastic articles from a continuous extrudate. Rotary punches are commonly used to form such articles, wherein the extrudate is fed between a synchronized, rotating pair of mating punch and die. The punch and die simultaneously sever the extrudate and form it to a desired shape. Rotary punches, however, suffer from several drawbacks. First, the punch and die are relatively expensive. Second, the punch and die are designed for a specific application, and generally do not include any adjustability (i.e., punch and die generally cannot be adjusted to form different size articles). Third, tooling and maintenance costs are relatively high, with replacement parts, including tooling, often being only obtainable from the original manufacturer.
Separately, techniques have been developed in the prior art for using a rotary straight-edged knife for severing an extrudate into desired lengths. The following patents disclose such a technique: U.S. Pat. No. 2,082,833 to Haupt; U.S. Pat. No. 4,585,600 to Rollyson et al.; and, U.S. Pat. No. 4,740,149 to Kristensen. The severed lengths, however, have straight, planar ends defined by the straight-edged knife. Any additional shaping and forming required for the severed lengths must be done in further steps.
It is an object of the subject invention to provide a method and apparatus for forming plastic articles having non-planar ends.
It is also an object of the subject invention to provide a method and apparatus for simultaneously severing and forming predetermined lengths of an extrudate.
The aforementioned objects are met by a method and apparatus for simultaneously severing and forming predetermined lengths of an extrudate to form plastic articles. The method and apparatus rely on a cutting blade having at least one non-linear cutting edge. The cutting edge is defined on the cutting blade which is mounted on a rotating cutter. The rotating cutter is disposed adjacent to a continuous extrudate, such that the path of travel of the cutting blade intersects the path of travel of the extrudate. In this manner, upon rotation of the cutter, the cutting edge causes a length of the extrudate to be severed from the remainder of the extrudate. Simultaneously, the non-linear cutting edge imparts a non-planar shape to either the severed end of the predetermined length or the remainder of the extrudate. It is preferred that the cutter have at least two non-linear cutting edges so that the trailing edge of a severed end of a predetermined length of extrudate can be simultaneously formed with a desired shape as well as the leading end of the remainder extrudate. Thus, both ends of a predetermined length can be formed with non-planar ends. After being severed and formed from the extrudate, the predetermined length of extrudate is allowed to cool to form the article.
The method of the subject invention is particularly well-suited for forming elongated articles having rounded ends, such as popsicle sticks, and spreading sticks for applying spreads, cheeses, and other comestibles. Furthermore, the rotation of the cutter and/or the feed rate of the extrudate are preferably adjustable to vary the predetermined length of extrudate that is to be cut, and the cutter can be readily replaced to enable the formation of different shapes on the ends of the articles. With these two features, the subject invention provides versatility in allowing for various sized products to be formed.
The invention will be better understood through a study of the following detailed description and accompanying drawings.